If you are suspecting that IPv6 is causing some issues in your environment you may want to completely disable it to rule it out. When you remove the checkmark for IPv6 from the network adapter this does not completely disable the IPv6 protocol, it still remains enabled for tunnel and loopback interfaces.
When you try to “ping localhost” you may see it respond with ::1:, this is the IPv6 loopback address. You can try to “ping localhost -4” to get a response in ipv4 format but the purpose of this is to completely disable IPv6 and make IPv4 the default response.
These instructions work in Windows Vista, Windows 7, Windows 8, Windows Server 2012.
In my personal experience I had to disable IPv6 when I was installing certain software which was registering itself to other components and instead of choosing IPv4 it was registering itself with IPv6 and was causing all sorts of issues. Disabling IPv6 and re-installing the software allowed it to install correctly and then I was able to re-enable it again.
1. Start > Run > Regedit
2. Navigate to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\TCPIP6\Parameters
3. Create a new DWORD (32 bit) named DisabledComponents
4. Set the value to Hex: ff. (To enable IPv6, enter Hex: 0)
Ping localhost before the registry change, reply is from IPv6 loopback ::1: